CDC sees no evidence of bioterrorism in spread of West Nile virus

Sep 19, 2002 (CIDRAP News) – In response to a US senator's speculation, the Centers for Disease Control and Prevention (CDC) says there is no evidence that bioterrorism has played a role in the spread of West Nile virus to and within the United States.

"As stated repeatedly, we have no scientific evidence to suggest that West Nile virus and West Nile activity in the United States is an act of terrorism or bioterrorism-related," Bernadette Burden, a CDC spokeswoman in Atlanta, told CIDRAP News yesterday.

Last week Sen. Patrick J. Leahy, D-Vt., whose office was the target of an anthrax-laden letter last fall, speculated on a radio talk show about the possibility that the West Nile epidemic is related to bioterrorism. The disease reached the United States in 1999 and spread rapidly across the country this summer. As of Sep 18, the CDC reported 1,641 confirmed cases in 32 states, with 80 deaths.

"I think we have to ask ourselves: Is it coincidence that we're seeing such an increase in West Nile virus, or is that something that's being tested as a biological weapon against us?," Leahy said on a Sep 12 talk show, as quoted by the Associated Press. The show reportedly was aired by WKDR in Burlington, Vt., and WDEV in Waterbury, Vt.

In a written statement released later the same day, Leahy said, "In the times in which we live, questions about our vulnerabilities are unavoidable, and finding all the answers we can is more important than ever. I have no way of knowing what the answers are, but some legitimate questions have been asked, especially before September 11 last year, and no doubt they are being asked anew by the agencies that are working on this."

Blythe McCormack, a Leahy spokeswoman in Washington, said Leahy was not calling for a new investigation of the issue. "It was basically along the lines of, 'We should be looking into every possibility, especially in the environment after September 11,'" she told CIDRAP News. She also said the talk show was cut short so that the station could broadcast President Bush's speech to the United Nations, so Leahy's comments were "kind of incomplete to begin with."

In subsequent news reports, CDC officials said the spread of West Nile in the United States has been consistent with what is known about its natural transmission pathway from mosquitoes to birds and people.

Burden said the CDC considered the bioterrorism possibility when West Nile first reached the East Coast in 1999, killing seven people in the New York City area. "The CDC considers any and all possibilities for a virus coming into the United States for the first time, so certainly the issue of it being planted deliberately was a question that was examined at the time," she said.

In October 1999, the New Yorker magazine published an article describing claims by an alleged Iraqi defector that Saddam Hussein was planning to use West Nile virus as a weapon. The article, by Richard Preston, said bioweapons experts at the CIA had heard of the claim made in a book by the alleged defector, who called himself Mikhael Ramadan, and they recalled the claim when West Nile virus was identified in New York City in September 1999. Ramadan's book, as quoted in Preston's article, said Hussein had boasted that his scientists would develop a strain of West Nile virus "capable of destroying 97 percent of all life in an urban environment." (The fatality rate for West Nile is far below 97%.)

Preston's article also quoted an unnamed Army expert as saying that Soviet Russian biologists had evaluated West Nile as a possible biological weapon but concluded that it wouldn't work very well.

After the New Yorker article appeared, the CIA said it had looked into the possibility that Saddam Hussein had engineered the West Nile outbreak and had concluded there was no evidence. Leahy's office supplied a copy of a Washington Post article published Oct 12, 1999, in which an unnamed CIA official said the agency had found no evidence of bioterrorism. CIA officials said the agency had reviewed press reports on the matter but had not conducted a formal investigation, according to the article.

One Congressional committee also looked into the issue in July 2000 and likewise saw no evidence of terrorism behind the West Nile outbreak. The report, by the minority staff of the Senate Governmental Affairs Committee, stated, "U.S. law enforcement, public health, and intelligence officials have investigated the possibility that West Nile virus resulted from a bioterrorist attack but believe that this is very unlikely. All indications point to the natural occurrence of West Nile virus, which probably arrived in New York through international trade and travel."